swapon error

[Seth Clarke]

Swap was getting full and OVO sent out a critical message. I created another LV and attempted a swapon but recieved this error.

Kernel tunable parameter "maxswapchunks" needs to be increased to add paging on device /dev/vg00/lvol6 (lvol 6 is 250 pysical extents)

I then opened SAM and changed the parameter but it gave me another error

semmnu must be <= (nproc - 4)

nproc = 4096
semmnu = 4096
maxswapchucks = 384

So I reduced semmnu to 4088 and raised maxswapchunks to 1024 and processed the new kernel and rebooted. But the parameters didn't change and I still couldn't perform the swapon

Any ideas why the tunable parameters didn't change. Any log files that I should check?

[Steven E. Protter]

Kernel processing appeared to fail.

There may be missing files in the /stand directory.

There should be a log of the problem. Perhaps try processing it with sam, there will be a command and error log.

Make sure /stand isn't too full.

SEP

[Ermin Borovac]

Have a look in /var/sam/log/samlog. There may be some clues in there.

[Seth Clarke]

I'll attach the samlog but it just says that everything completed successfully.

Also, /stand has 217MB available

[Patrick Wallek · Accepted solution]

Run the following:

# grep -e nproc -e semmnu -e maxswap /stand/system

And see what the results are.

It appears to me from your log that only semmnu was changed. I did not see anything in the attached log about maxswapchunks.

Try changing it again. Also, if you are going to raise the value of maxswapchunks, go ahead and raise it to its maximum (16384). That way you NEVER have to worry about that particular kernel parameter again.

[Seth Clarke]

I probably didn't get enough of the samlog to show the change of the maxswapchunks

here's the output from the grep

maxswapchunks 1024
nproc 4096
semmnu 4088

They are what they should be but SAM does not show them as such

[Victor BERRIDGE]

Hi,
Did you change your params in 2 steps? I mean changing then before rebooting decide to do some more corrections?

Anyway my 2 cents would be having swap issues can be avoided by configuring maxswapchunks to a decent value (in your case 2048) which leaves you enough flexibility to add if needed more swap without having to reboot...


All the best
Victor

[Seth Clarke]

I may have found the issue, but am presented with another issue. I was going through the process list and saw processed from days ago, then did and uptime and saw that it was up for weeks. Which means that when the kernel was processed with SAM it didn't actually reboot. I lost my shell and the network went down but I don't think that it actually rebooted. I may have to perform a halt or shutdown -r to see if it actually boots. That would explain why the grep gave me the correct parameters.

[Tony Scully_2]

Seth,

I have occasionally seen this kind of hang when using X11 SAM to change kernel parameters. The session you are using dies, but the server stays up. When I can I use a console session to make kernel changes, or use the cmd line. As you have suggested it's worth a reboot -- it looks like the parameters have been updated in the new kernel, but that one needs moving into place.

Tony

[Seth Clarke]

rebooting the system was crucial. It did not shutdown after the parameter change. An in house application delayed the shutdowns